


Test Subject Hero

by Ice_ice_bby



Category: Portal (Video Game), 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia
Genre: Accidental recruitment, Canon-Typical Violence, Crossover, Gen, Implied/Referenced Character Death, Minor Injuries, Muteness, Near Death Experiences, Other Additional Tags to Be Added, Panic Attacks, Post-Portal 2, Tags May Change
Language: English
Status: In-Progress
Published: 2020-07-05
Updated: 2020-08-14
Packaged: 2021-03-04 21:21:09
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 4,040
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25083022
Author URL: https://archiveofourown.org/users/Ice_ice_bby/pseuds/Ice_ice_bby
Summary: Set in the aftermath of Portal 2, a boy gains freedom from his old testing life from Aperture Science Laboratories. But as he tries to find his way around the surface, accidentally stumbling into UA, Mathieu is exposed to the world of becoming a hero.Will he accept the path of becoming a hero, or will he go down the path of something else?(READ THE OPENING NOTES BEFORE READING!)
Comments: 4
Kudos: 24





	1. Got Lemons? Get a Student.

**Author's Note:**

> Okay so I finally decided to delete the _ORIGINAL_ Test Subject Hero
> 
> I'm sure I could've orphaned it, but I dunno. Will I regret it? Probably, but whatever. 
> 
> I'm basically rewriting the whole story, and I figured deleting the original story would be easier since I don't have to more or less rewrite whole chapters and make the story more confusing than it would originally be if I simply kept the original story up and just individually replaced all 17 chapters. 
> 
> That being said, whether you're an old fan or new fan of the original work, welcome! Hopefully this new version will be better :)

**Summary for the Chapter:**

> Mathieu is finally free from Aperture, but he has no idea where he should even go. 
> 
> After days running, Mathieu finds himself outside of UA. 
> 
> However, his welcome to UA may not be as warm as the sun he learns to enjoy. 

Lemons. If life gives you lemons, don’t make lemonade! Make life take the lemons back! Get mad!

That quote rang through his head as he ran, Mathieu Kiyota. Get mad, Cave Johnson said! Get angry! And, he did. Mathieu got angry and managed to leave Aperture with little to no injuries. Well, at least to his knowledge. And it wasn't exactly _anger,_ but more like secondhand anger and sheer determination. 

Same thing, right?

Well, injured or not, Mathieu ran anyway. And he wasn’t alone either, carrying the Companion Cube with him every step _away_ into a new life. 

Or Mathieu would be stepping into a new life if he had a sense of direction. Mathieu figured he was pretty far from the out of place shed in the middle of nowhere. But that didn’t mean much when Mathieu was running away blindly, only having the clothes on his back and a cube that he couldn’t bring himself to just leave behind. 

Open fields of grass and dirt were nothing like an enclosed space. Grass and dirt weren't the plain walls of Aperture that Mathieu was used to. The sun was hot and brighter than he remembered, not like the flickering fluorescent lights that were in Aperture. He wasn't used to the sun, nor was he used to just....walking with no place to go in mind. 

But the grass and dirt was nice. He could see everything, mostly. There was nowhere to hide, except for trees here and there, and breathing clean air was nice. It felt good and he felt good. 

Too bad the good feelings would come to an end pretty soon.

* * *

It was getting dark and Mathieu was _exhausted_. 

He had no idea how long he had been walking and running for. He would stop every so often, but only for a short while. Mathieu couldn't just _stop_ moving, not until he felt safe enough. 

Mathieu had made it into civilization, being more confused by the loud noises and so many overwhelming sights and smells. He didn't feel any safer, and the smell of food reminded him of how _hungry_ he was. 

His legs and arms ached, the Companion Cube felt like a sack of bricks with a new brick being added with every new step. Mathieu had to stop, everything hurt so _badly_. His throat began to hurt again, it had been a whole day since his last drink. 

But no. He had to keep going. 

But where was he even going? Mathieu had no idea anymore, a home would be nice. A nice home where he could do normal people things, whatever people who weren't test subjects did. 

But alas, that seemed unlikely. Especially with, again, Mathieu's poor sense of direction when in an open space. His thoughts raced at what a normal home would look like, it'd be like the home he used to live in. The home when he was 7, with a pair of parents waiting for him at the front door. 

Mathieu suddenly felt himself tilting over. 

_'This isn't_ good.', Mathieu could only think as he let the Companion Cube slip out of his hands. He caught himself before completely falling over, realizing that he should probably get some sleep. Mathieu pushes himself up off the hard ground, glancing around in the dark. He couldn't climb a tree, not in his current state. And the ground was hard and cold. 

Not that he should've cared, but passing out on the cold ground was going to be a faint memory from Aperture. Nothing more than a bad dream. 

Mathieu slowly pushed himself on, looking to maybe find a place that would pity him to let him stay for a night...or three. Or at least he was, until he stopped outside of a building. A gated building.

Staring up at the sign, Mathieu frowned. UA. That name was familiar, but he just couldn't put his finger on it. Well, it's not like they'd _mind_ if he stayed there for the night, right? And besides, it wasn't like Mathieu would be passing through the gate. He had a quirk, after all. 

He stared down at his hands for a second or two, giving the gate in front of him some space. With two snaps of his fingers, two portals appeared. ' _Perfection._ ', Mathieu thought as he first pushed the cube through the portal, then himself. But now what? 

He was so tired, and he was tired of walking for long. Mathieu felt the exhaustion take over, falling asleep as soon as his body basically hit the ground. The cool grass was nice, and he....felt nice. 

The nice feelings would soon be replaced by an explosive personality.

* * *

Katsuki "King Explosion Murder" Bakugou was absolutely fuming. 

' _How_ ** _dare_** _Deku humiliate him like that?! The fact that....DEKU could just_ ** _copy_** _him, with the skills_ ** _he_** _actually took the time to master!_ ' Bakugou angrily thought to himself, storming to school one morning. The thought of the green haired boy would've made him start swearing up a storm, but he wasn't going to do that today. Apparently that was "rude" and "uncalled for". And he should try "being nice" and "not cursing out his peers". How annoying. 

Bakugou was about to head into the building before suddenly hearing a noise. 

"Probably a stupid cat." He mumbled, trying to push away the slight curiosity to check out the noise. What was he, Deku? 

Well, he might as well call himself Deku because his curiosity _did_ get the better of him. Bakugou stepped over to the bushes and trees, thinking about how this was such a waste of time. When he moved the bushes, he would see some cat. A cat who would dash away to hide somewhere else on the school grounds. 

What he saw was NOT a cat. It was....a person?

"What the fu-" He began to yell, stepping back and almost stepping back into the tree behind him. It was a sleeping person, or well...sleeping kid? A kid, looking no older than 12, who had made a _nest of_ bushes. Bakugou didn't know what to do. He scowled down at the kid, gently tapping them with his foot. 

The kid didn't move, so he tapped them harder. "Oi, kid. Get up!" He loudly cleared his throat, watching them slowly wake up. The kid looked dazed, like they had been woken up from a nap. 

The kid suddenly locked eyes with Bakugou, slowly standing up. Having trouble balancing, those weird looking boots didn’t help with that, the kid wiped the dirt off their cheek. They were quiet, in a creepy way, and seemed to expect _Bakugou_ to do something. 

Bakugou scowled again, what was this kid's deal? He, if he were to be honest, wanted to know what this kid was doing at UA in the first place. He gave it some thought, only being able to conclude that the kid must've snuck in. How the kid snuck in wasn't Bakugou's problem, his problem was getting to class on time. 

He didn't say anything, turning around to dash to class. Or, well, he would've if the kid hadn't _followed_ him. The kid was staring at him with big brown eyes, probably expecting the blonde to let them tag along. 

"Scram kid, you're not allowed to be here." Bakugou said, as kindly as he could with making the kid cry. They weren't budging. In fact, the kid took it pretty well and tilted their head in reply. 

They turned back to their bush nest, turning back to Bakugou with a disappointed stare. Great, now what was he supposed to do? 

Pinching the bridge of his nose, he decided it would be for the best of _both_ of them if Bakugou just left the scene. He was sure if he just walked away, the problem would simply go away on its own. 

So, after what felt like forever, Katsuki headed to class. If that kid made him late, he was surely going to make _someone’s_ life hell. 

Too bad he was unaware of who decided to tag along. 


	2. Welcome to Test Chamber 1-A

**Summary for the Chapter:**

> Mathieu gets overwhelmed with the amount of people who are staring at him, but he can't help but notice that one of them looks pretty familiar.

This had to be the first time Mathieu has entered a school in the last nine years. Well, nine years and a half. 

He had been six, going on seven, before he had been pulled out of school in favor of homeschooling. Being so young, Mathieu preferred being home schooled to avoid getting bullied. Why? For being seen as quirkless. 

Thinking back on it, he sort of understood their reasoning. Little kids didn't always understand how tearing a small hole into time and space was a quirk, and if they couldn't see it, it didn't exist. But it was always awkward to feel their glaring stares when he'd walk through the school hallways, thinking about how he was quirkless. 

And that's how he was feeling right now. 

As Mathieu followed the blonde and loud student into the school, he could feel the stares of other students burning through the back of his head. He was sure they were whispering about him, but he didn't know what. Maybe about how he suddenly appeared? Or how he was dressed? The eye catching orange jumpsuit and long-fall boots weren't good for staying hidden. Or even the weighted companion cube? He didn't know how that would bother them, unless they were jealous. 

But eventually, Mathieu lost sight of the loud student, realizing that he was alone in the hallway. Mathieu frowned and set the weighted cube down, not sure where to go. Just because he was familiar with school, didn't mean he exactly remembered how the long hallways worked. Aperture's hallways weren't this long, and they didn't have so many doors. Well, most of the doors were locked, but that wasn't the point. Mathieu was lost. 

So, he decided to just wander the hallways. He was sure if he found someone, they would be kind enough to explain where he was. And hopefully not kill him. 

Mathieu let out a sigh, slowly walking down the hallway. The hallways were quiet, and it made Mathieu nervous. He walked over to the large windows, pressing his hands against the glass. The glass is a little warm from the sun and his body heat, leaving sweat prints. Mathieu can just barely see his reflection, a scruffy and exhausted looking boy with baggy clothes. 

Mathieu doesn't know what to think. He's a little disappointed that he isn't taller, but seeing his reflection helps him relax a little. 

After a few minutes of admiring his reflection and the warmth of the sun, Mathieu resumes wandering through the quiet halls of the large school. It helps him get his bearings, and he feels like he isn't wandering around _too_ blindly. It also gives him time to think. 

Mathieu has no idea where he could go. 

As much as he'd like to, he's positive he can't live in a school. And he has no money, GLaDOS made him leave and he didn't even consider what he'd do next. He just ran as far away as he could. His heart begins to pound anxiously, now beginning to think that maybe GLaDOS was setting him up. Setting him up to die, just not by her own doing. She did sometimes taunt him by bringing up how she was going to live forever. 

Mathieu feels his chest tighten and he suddenly can't breathe, his legs feel weak. 

Mathieu steps back, needing to lean against something to relax. He leans against a door, slamming a little too hard on it as he struggles to catch his breath and think straight. He doesn't register the door he's leaning against opening and the way he's standing makes him fall to the ground. 

He lets out a pained groan, squeezing his eyes shut from the sudden bright lights. 

He can barely hear a "are you okay?" from a voice above him, but he really doesn't want to open his eyes. Mathieu only opens his eyes when he hears the voice from earlier. "It's that twerp from outside!" 

Mathieu sits up, rubbing his head with a pained expression. ' _That's going to leave a bruise later._ ', he thinks as he turns around. There are people staring at him. Not with glaring expressions of how he got here, or that he was quirkless, but just staring. 

Mathieu stares back with wide eyes. 

Mathieu doesn't know whether to freak out and try to run, or if he should stay calm and try to explain himself. He stands up slowly, his legs wobble from his panic and his boots not cooperating with his movements. The floor is smoother than the floors at Aperture. 

He feels a hand on his shoulder, Mathieu jerks his shoulder back as the person slowly moves their, no, his hand back. 

The person then asks: "Are...are you okay? Sh-...should we get the nurse or...?" He stammers awkwardly, his eyes dart back and forth as Mathieu can only tilt his head. A nurse? What would they do to him? 

But Mathieu slowly nods in reply, he feels a little better than earlier. He feels fine enough to move. 

Mathieu takes an uneasy step forward, the boy standing in front of him steps back. They continue to do that for a second, Mathieu stares into the boy's wide green eyes. He looks almost bothered that Mathieu hasn't said a word the entire time, nor has Mathieu seemingly noticed the other people in the room. 

Mathieu lets out a sigh, he had no idea what he was doing. This wouldn't solve anything, he probably looked so out of place anyway. 

He begins to turn around to leave the classroom, but someone clears their throat. 

Slowly turning around, Mathieu locks eyes with the tall man in the room. He assumes that's the teacher, but he looks so tired. 

Mathieu tilts his head as he stares at the teacher. For some reason, the teacher looks familiar. 

But he doesn't exactly know why. Weird.

"Who are you?" The tired looking teacher asks, Mathieu doesn't know what to do. 

He doesn't want to answer, and he really doesn't know how. 

He opens his mouth, and all he can do is let out a little whine.

He would speak, explain where he came from and maybe even try to beg for somewhere to stay. But the words feel heavy on his tongue and he's almost scared his words would be used against him.

Mathieu takes an uneasy step back, he can't bring himself to look away from _everyone_. His legs hurt, and he can't move. The teacher then asks the question that the green haired boy had asked him: "Are you okay?" 

Mathieu doesn't shake his head, nor does he nod. He feels too stiff and can't move, he has to leave. 

"Nngh..." Mathieu mumbles, lets out a breath and turns to leave. He can feel the people in the room staring at him, but he tries to ignore it. He tries to convince himself that anyone would stare if they saw someone in a bright orange jumpsuit and weird looking boots. 

He just has to leave, and he can come back later. When there's less people staring at him. 

The teacher doesn't seem that worried, the tired looking expression doesn't help much. He doesn't know what to do with Mathieu, seeing how the boy reacted to one of his students. He lets out a sigh, hoping that this could work.

"It-...." He hesitates, Mathieu notices. "It's okay. You're not...in trouble. You can stay here, until after class." The teacher explains and Mathieu hesitantly nods. Looking up at the teacher, Mathieu nods again with a bit more confidence. 

The teacher said it was okay to stay, Mathieu feels himself relaxing. He could wait, waiting was easy. 

As the teacher heads back to his position in front of the class, Mathieu quietly goes to back of the classroom, sitting in the empty seat. Compared to the other people, he looks so out of place. 

No uniform, or books with him. Only a large cube and his clothes from Aperture. 

Mathieu pouts, not too sure when class would end. It's still morning, he assumes. And from his experience with school and homeschooling, class might last for a while. 

Kicking his legs impatiently, Mathieu shakes his head. He should focus on the lesson, class would end....eventually. 


	3. Don't be Alarmed, Explain Yourself

**Summary for the Chapter:**

> Mathieu has to explain where he came from. But he can't just _say_ it, can he? No one would ever believe him. 
> 
> But maybe it would be a lot easier to explain when he drew it out, anyway.

Sooner or later, the class _finally_ ended.

Mathieu felt like the class would never end. He was half asleep, smacking his lips tiredly as he watched the students leave the room. 

As he had been waiting, it gave him the time to observe them. 

It wasn't much, but Mathieu didn't have anything else to do. Plus, Mathieu liked seeing little habits that people would just do for no explained reason. 

Like that green haired boy from earlier, he didn't seem to ever stop moving. If he wasn't physically moving, his hands or feet would be moving. And there was a tall boy with glasses, Mathieu noticed that he often mumbled things to himself. Even though Mathieu couldn't see his face, Mathieu could see his body perk up occasionally. And the loud, blonde boy too. Mathieu noticed how he'd get tense if the green haired boy would answers something correctly, but he also would brag about getting things right. 

It reminded him of someone. He just couldn't put his finger on it. 

But the classroom was soon empty, excluding Mathieu and the teacher. 

The two stared at each other for an uncomfortably long time, a whole minute. The tired looking man was about to say something, Mathieu quickly stood up. 

As the two of them left the classroom and walked down the hallway, Mathieu couldn't help but notice how quiet the hallways were now. 

Although maybe it was just because, despite not attending public school for over 8 years, Mathieu was a little used to seeing more people. And there had been the crowded streets outside, Mathieu was amazed that there could be so many people all at once in, well, anywhere! 

He began to run ahead, almost forgetting that he was being escorted somewhere. 

The teacher who was being left behind cleared his throat, getting the boy's attention. Whoops, Mathieu was getting ahead of himself. 

Slumping his shoulders, Mathieu stopped to let the tired looking teacher catch up.

* * *

The two of them finally did stop walking, Mathieu looked confused. What room was this? 

Mathieu observed the teacher, watching him open the door to this new room and lead him inside. Eventually the pieces began to click together, and Mathieu turned to the tired man with wide eyes. 

The principal's office! Of course!

Although, Mathieu had no idea why he would have to go here. He wasn't in trouble, at least he hoped he wasn't. All Mathieu had done was sit in a classroom! Although, he failed to remember that he _technically_ also kind of broke into a school. 

"So this is the boy who showed up?" The principal suddenly said, motioning a paw to Mathieu. The teacher nodded. Mathieu gawked at the principal sitting in front of them, the principal was so... _small!_

"Mhm. He appeared outside of the classroom, although I don't exactly know how...." The teacher trailed off, getting a nod. He gave a glance to Mathieu who had been standing next to him the entire time. The principal motioned for both of them to take a seat. 

"Oh? I'm surprised he got past security. And, as far as I know, you're the only one who has alerted me of his presence!" The mouse- cat, dog thing principal said, pouring the two of them some tea. The teacher didn't accept his and Mathieu simply stared at the cup in front of him. 

A drink sounded nice, but this....animal was strange. 

He couldn't just accept tea from a strange animal, could he? No matter how thirsty he was. 

The three of them sat in silence for a painfully long minute. The only sounds in the room were the sounds of soft breathing, the ticking clock on the wall, and the soft sips of tea. 

"Alright. I suppose we should get down to the important matters then. If you don't mind me asking, what's your name?" The principal asked, getting a confused head tilt from Mathieu.

He glanced down, his mouth suddenly felt dry. Maybe Mathieu _should_ drink that tea. He awkwardly picked up the cup of tea to gulp it down. "Mmm...." Mathieu began to mumble, trying to answer. He could answer this question easily. It was just to say his name, how hard was answering that?

Apparently too hard. 

"Mmm....ahh...?" The only noise came out of his mouth, scowling afterwards in frustration. 

'How embarrassing...is this that brain damage thing they mentioned...?' He thought, thinking back to how Wheatley and GLaDOS would mention that he apparently had brain damage, or at least that he wasn't exactly too sharp after being frozen for a while. 

The principal simply nodded at his response, although he looked a little confused. 

Hopping out of his seat, the principal went over to the filing cabinet. Mathieu glanced over at the teacher, he didn't glance back. 

Mathieu felt embarrassed now. Not only did he break into a school and had nowhere to go, but he couldn't even explain his reasons for his actions either. He could think of what he wanted to say easily, but the words were just _stuck_ on his tongue. 

His heart pounded in discomfort, but Mathieu perked up when the animal principal returned with some papers and a pen. 

Oh. _Oh._

He could just write it out! 'Easy!' Mathieu thought, taking the paper and pen. All he had to do was write what he wanted to say. 

Or well, he would've if he knew how to say it. He felt frustrated. 

But, Mathieu was going to do something. Maybe if he drew a line just so he could get his thoughts together. A line that soon turned into a box, representing Aperture Laboratories. And then there were arrows, leading away from the box building. 

And then he turned to the next sheet of paper, drawing the front of UA. Or at least what he had seen yesterday, and some lines to show how he got in. 

Mathieu suddenly frowned in thought, this didn't explain much. He had forgotten to write something, and he had wasted paper with silly drawings. But as Mathieu was internally worried about what he hadn't done, the teacher and principal picked up the papers to see what he had done. 

"Well, that clears up one issue. I had a feeling it was quirk related, but I didn't think it would be this complex." The principal almost sounded amused, switching papers with the teacher. 

Mathieu suddenly nodded in agreement, pointing to one of the drawings, showing a rushed drawing of Mathieu looking exhausted but moving away from something. The principal seemed to understand. "Right, I see. You must've come a long way from....this place." Well, at least he understood that Mathieu was not from around here. "But this does lead to a few more problems." He suddenly said, the teacher quietly nodded. Mathieu awkwardly shrunk back. 

"I will be right back. I just need to make an important phone call." The principal said, hopping out of his seat. Mathieu couldn't help but crack a small smile, the principal was pretty okay. A little weird, but okay. 

The teacher awkwardly cleared his throat. "You know, you're fairly lucky. Most people would be considered trespassers, especially with you...somehow not getting caught by security. But...well, I guess I can't blame you for seeking shelter here. Even if these...drawings don't make sense." The teacher said, mumbling the last part. 

Mathieu didn't understand, well, some of it. He had forgotten that he could've gotten in trouble for this. And he figured the teacher was right, he was lucky that he had passed out last night. If he had snuck in any other time, he was sure that he wouldn't have been able to get a chance to explain himself. 

Mathieu leaned back in his seat, now he had to wait for the principal to return. 

**Notes for the Chapter:**

> the ending was a little hard to write eep, but i wonder what the phone call is about :3c

**Author's Note:**

> So this is for basically if you didn't understand the notes at the top, in summary, I've basically deleted the original Test Subject Hero in favor of rewriting the whole story. 
> 
> I don't know how well it will go, but I have pretty high hopes and I hope that you, the reader, will be able to enjoy this new version as much I do


End file.
